Electric regulator



Jan. 31, 1933. STOLLER 1,895,498

/ ELECTRIC REGULATOR Filed June 11, 1919 Patented Jan. 31, 1933 UNITEDSTATES PATENT OFFICE HUGH M. STOLLER, 01' NEW YORK, 11'. Y., ASSIGNOR TOWESTERN ELECTRIC COMPANY, INCORPORATED, 0] NEW YORK, N. Y., ACORPORATION 01' NEW YORK ELECTRIC REGULATOR Application filed June 11,

This invention relates to a novel type of regulator which is applicablein general for the regulation of electric circuits, and is particularlyadapted for controlling a motor in order that its speed may beregulated.

The regulator provided according to the present invention is of thethermionic type and comprises a vacuum tube containing electrodes. As iswell known in the art, the cathode of a vacuum tube serves as a sourceof electrons that travel to the anode or plate electrode and the amountof this electron stream or space current depends upon several factors,primarily upon the temperature of the cathode, an increase intemperature producing a larger space current. It is also well known thatchanges in the temperature of a cathode create much more thanproportional changes of the space current, and consequently of theinternal impedance of the tube, so that a vacuum tube may be made torespond very readily to changes in the temperature of the cathode.

In accordance with this invention a characteristic of an electricalmachine such as the speed of a motor, may be re lated by connecting anexcitin windin o the motor in circuit with the cat ode an anode of thevacuum tube, and by supplying the cathode with heating current whichvaries with the speed of the motor or with the voltage suppliedthereto., One way in which the heating. current may be made to respondto the speed of the motor is to provide means for producing analternating current which varies in frequency in accordance with chan esin speed, and supplying the cathode with said current through theintermediary of a circuit tuned to a frequency preferably higher thanthe maximum fr uency of said current. The intensity of t e current insaid tuned circuit will then depend upon the frequency of the currentimpressed thereon and consequently upon the speed of the motor. Thetemperature of the cathode and consequently the. effective impedance ofthe tube will therefore respond to changes in the speed of the motor, sothat the variations in the tubes impedance may so modify the currentthrough an exciting winding of the mo- June 8, 1918; Peter Irving Woldand 1919. Serial No. 808,886.

tor as to bring about the desired regulation.

As is well known in the art, the space current of a vacuum tube at firstincreases very rapidly with increase in plate voltage but after acertain value of plate voltage, dependent upon the temperature of thecathode, is reached the space current remains substantiall constantregardless of further increase in p ate voltage. In utilizing a vacuumtube as a re lator it has been found preferable to have t e tube operateon that art of the curve above described where a wi e variation in platevoltage will not produce any appreciable change in the space current.

The electric regulator of the thermionic type possesses many advantagesover regulators of other types in that it is sim 1e, efiicient, light inwei ht, and substantia 1 free from sparking. ther advantages will beapparent from the detailed description of this invention.

Reference is made to the following co end ing applications which relateto regu ators of the type emplo ed in this invention: Hugh M. Stoller,erial No. 230 192, filed April 22, 1918; Hugh M. Stoller, Serial No.231,586, filed April 30, 1918; Hugh M. Stoller, Serial No. 244,636,filed July 12, 1918; Peter Irving Wold, Serial No. 238,9506 filed liverE. Buckley, Serial No. 250,883, filed August 21, 1918; and Peter IrvingWold, Serial No. 247,275, filed July 29, 1918.

As a thermionic device may be associated with an electric motor in avarietyof ways several forms that this invention may assume will now bedescribed in detail in connection with the drawing, in which Fig. 1illustrates the thermionic regulator of this invention applied to varythe current through an exciting winding 0 a motor inresponse to chan esin its speed; in Fig. 2, the heating current or the cathode of thevacuum tube regulator is supplied by a small generator which is drivenbv the motor to be regulated; Fig. 3 is a modification of Fig. 2; inFig. 4, the cathode of the thermionic regulator is supplied through atransformer with a heating current which varies with the speed of themotor; and Fi 5 is a curve illustrating ,how the current in a tunedcircuit changes with the impressed frequency.

Fig. 1 shows how this invention may be applied to the regulation of thespeed of a shunt-wound motor, 8 is a motor connected throughmains 9 and10 to a suitable power supply. In circuit with the exciting winding 11of the motor are the anode 12 and cathode 13 of a vacuum tube 14.Heating current for the cathode 13 is supplied bya source of voltage 15.The current through the exciting winding 11 depends upon the temperatureof the cathode 13, so that any change in the temperature of the cathodeWlll vary the current through the exciting winding 11 and consequentlyvary the speed of the motor. Mounted on the axle 18-of the motor are acentrifugally controlled contact 19 and a relatively stationary contact20 which are electrically connected to slip rings 21, 22 respectively.Brushes on these rings are connected to the terminals of a resistance 25which is in circuit with the cathode 13 and battery 15. Contact 19should be so designed as to close when-the speed of the motor exceeds apredetermined value while breaking contact at a somewhat lower value,these two values preferably being the limitatipn of range of fluctuationpermissible in the speed of the motor 8. For example, in a case wherethe normal speed of the motor is 1800 R. P. M., these uper and lowerlimiting values might be 1830 P. M. and 1770 R. P. M. respectively.

The manner in which the speed of the motor 8 may be controlled by suchan arrangement may be explained as follows. If while the motor is runninat normal speed, the voltage supply should suddenly be increased, or theload on the motor would decrease, there would be a tendency of the speedof the motor to increase. As soon as the speed of the motor reaches theupper limiting value mentioned above, which in the case illustrated is1830 R. P. M., the contact 19 will close, thereby short-circuitingresistance 25 and increasing the current supplied. to filament 13. Thiswould decrease the impedance of tube 14 a more than proportional amount,thereby immediately increasing the current through exciting the speed ofthe motor. If, however, the speed would then decrease below the limitmgvalue of 1770 R. P. M., contact 19 would be opened again, therebydecreasing the temperature of the cathode and increasing the speed ofthe motor. It follows that the contact 19 would be made and broken so asto maintain the average temperature of the cathode 13 at such a value asto give the substantial constant speed desired.

In the arrangement shown in Fig. 2, the motor 30 has mounted on its axle31 a small generator 32 which supplies current to the vcathode 3301Vacuum tube 34. Space current for the tube is supplied from the leadswinding 11 and slowing up 35, 36 which also supply the motor 30 Themotor is provided with a main field winding 37 and an aiding winding 38,winding 38 is in series with the electrodes of the vacuum tube 34. Ifnow the speed of the motor would tend to increase, due for example, toan increase in the voltage across the leads 35, 36,-

the speed of the generator 32 would likewise tend to increase, therebyincreasing the temperature of the cathode-33 and the space currentthrough the tube and hence the current through the aiding winding 38,thus restrict ing the rising speed of the motor 30. Likewise a decreaseof the voltage supplied to the motor would decrease the temperature ofthe cathode and the current flowing through the aiding winding, so thatthe speed of the motor may be maintained at the desired value.

Fig. 3 illustrates another form that this invention may take in beingapplied to the reg ulation of the speed of a direct current motor whichis a shunt-wound motor having a main exciting winding 46 and anauxiliary aiding winding 47 One pole 48 of the field magnet of the motoris shown slotted so as to form a separate pole piece 49 around which isa winding 50 shunted between one of the main brushes 51 and anadditional brush 52. The winding 50 should preferably have more ampereturns than the winding 47. The motor, therefore, acts as a generator forsupply ing voltage across the terminals of this Winding 50 which, asshown, may be also connected to heat the cathode 54 of the thermionicregulator 55. The anode of this vacuum tube is shown connected to aterminal of the aiding winding 47.

The manner in which the vacuum tube 55 may regulate the speed of themotor 45 may be explained as follows. When the voltage across the leads56, 57 would increase, for example, thereby tending to speed up themotor, the voltage generated across the brushes 51, 52 would likewiseincrease, thereby increasing the temperature of the cathode 54.

This temperature change would-produce a more than proportional increasein the space current of the vacuum tube, so that the current through theaiding winding 47 would likewise be greater. This increase in thecurrent in the auxiliary winding would tend to strengthen the motorfield, thereby restricting the increase in the motors speed. In asimilar manner, if the voltage across leads 56, 57 would decrease invalue, the thermionic regulator 55 would decrease the current throughthe field winding 47, thereby weak- .ening the field and restricting thereduction in the speed.

In Fig. 4 the motor 60 has a main exciting winding 61 and an aidingwinding 62 connected between the supply mains 63, 64. In circuit withthe aiding winding 62 are the anode 65 and cathode 66of the thermionicregulator 67. The motor 60 has one of its commutator bars 68 grounded byhaving it electrically connected by a wire to axle 69. Connected betweenthe main brush 7 0 and a brush 71 which bears on the axle is a circuit72 containing a condenser 73 and the primary winding 74 of a transformer75. When the motor 60 is running, it is evident that this circuit 72would be su plied with a pulsating voltage which would be at a maximumvalue when the grounded commutator bar 68 is diametrically oppositebrush and zero in value when brush 70 is on the grounded coinmutatorbar. The secondary winding of the transformer 75 is connected across theterminals of cathode 66. Since the current in this secondary winding isproportional to the current of the circuit 72, it follows therefore thatthe average temperature of the cathode 66 will be proportional to thestrength of the alternating current in circuit 72. The frequency of thiscurrent will, of course, depend upon the speed of the motor, an increasein frequency being produced by an increase in speed.

As is well known in the art, the strength of the current in a circuitcontaining inductance and capacity is a maximum for the frequency ofcurrent to which the circuit is tuned and decreases rapidly in value asthe f uency changes to other values. I

1g. 5 illustrates a characteristic curve such as the tuned circuit 72may have in which the ordinates represent the intensity of the currentin the circuit and the abscissa; represent different values of theimpressed frequencies. It is preferable that the tuned circuit 72 betuned to a higher value of freuency than will be met in the regulationof t e speed of the motor, so that the variation in frequency, due tochanges in speed, would, for example, be within the range of the twopoints P and P on this curve. As may be seen from the drawing the curveis very steep between these two points, a small increase in frequency.or speed of the motor producing a very large increase in the intensityof the current in. the tuned circuit.

The manner in which the regulation is obtained in Fig. 4 may now bedescribed as follows. With the tuning of circuit 72 so adjusted that themotor gives a frequency of current in the circuit of a valueintermediatcthe points P P on its characteristic curve. suppose that the s eed ofthe motor would suddenly tend to increase. The frequency of the currentin the circuit 72 would consequently increase, thereby producing a muchgreater change in its current value. This increase in current would beimpressed through transformer 75 on the filament 66, increasing itstemperature and increasing the current in the aiding winding 62. Itfollows. therefore, that any change in the speed of the motor would sochange the current through the aiding winding 62 that the changes involtage, load, temperature or other circuit conditions.

With the arrangement shown in Fig. 4 it is important that the circuit 72be tuned to i such a frequency that the regulator 67 is able to sorestrict any rise in speed of the motor that the current supplied tocircuit 72 will never have a frequenc as high as the frequenc to whichcircuit 72 is tuned.

It is obvious that'this invention is not limited to the particular formsabove described, but that they may be considerably modified withoutdeparting in any wise from the spirit of this invention, as defined bythe appended claims.

What is claimed is:

1. In combination, an electric circuit contaunng'an electric machinehaving a stator and a rotor, a tuned circuit responsive to changes in acharacteristic of said electric circuit, and means comprising athermionic device responsive to the tuned circuit for regulating acharacteristic of said electric circuit.

2. n combination, an electric machine having a stator and a rotor, atuned circuit responsive to chan s in a characteristic of said machine,an a vacuum tube regulator responsive to said circuit for regulating acharacteristic of said machine.

3. In combination, an electric circuit containlng an electric machine, atuned circuit responsive to changes in a characteristic of said circuit,means comprising an electric discharge device having an anode and acathode for regulating a characteristic of said circuit, and means forheating said cathode through the intermediary of said tuned circuit.

4. In combination, an electric motor, a tuned circuit responsive tochanges in a characteristic of said motor, an electric discharge deviceregulator for controlling a characteristic of said motor and having acathode, and means for causing the temperature of said cathode to beresponsive to said tuned circuit.

5. An electric machine, a tuned circuit, means for supplying alternatingcurrent to said circuit dependent in frequency upon a characteristic ofsaid machine, means comprising a vacuum tube having an anode and acathode for regulating a charcteristic of said machine, and means forvarying the heating current for said cathode in response to variationsin the current in said tuned circuit.

6. An electric motor, a tuned circuit, means for supplying analternating current in said circuit dependent in frequency upon thespeed of said motor, means comprising a vacuum tube having an anode anda cathode for regulating the speed of said motor, and means for varyingthe heatingcurrentfor said cathode in response to variations in thecurrent in said tuned circuit.

7. A motor having an exciting winding, a vacuum tube in circuit withsaid winding, said vacuum tube having an anode and a cathode, and meansfor supplying said cathode with current which varies in frequency inresponse to changes in the speed of said motor. c

8. An electric machine having an exciting winding, a vacuum tube incircuit with said winding, said vacuum tube having an anode and acathode, means for supplying said cathode with current which varies infrequency in response to change in a characteristic of said machine. 7

9. In combination, a circuit to be regulated, a vacuum tube regulatortherefor having an anode and a filamentary cathode, a transformer, meansfor supplying to said cathode through said transformer alternatingcurrent varying in accordance with the characteristic to be regulated,and means responsive to said tube for controlling said circuit.

10. An electric motor having a commutator and an exciting winding, avacuum tube in circuit with said exciting winding, said vacuum tubehaving an anode and a cathode,

I one of said commutator bars being electrically connected with the axleof said motor, a brush on said axle, a transformer, a condenser, anelectric circuit comprising the primary of said transformer, saidcondenser, said brush on the axle of said motor and one of the mainbrushes of said motor, and electric connections between said cathode andthe secondary of said transformer.

11. An electric motor having an axle, a commutator and an excitingwinding, a vacuum tube in circuit with said winding, said vacuum tubehaving an anode and a cathode, an electrical connection between one ofsaid commutator bars and said axle, a brush on said axle, a transformer,a condenser, an electric circuit comprising the primary of saidtransformer, said condenser, -a main brush of said motor and the brushon said axle, whereby said circuit is supplied with a pulsating currentof a frequency dependent on the speed of said motor, said circuit beingtuned to a frequency eater than the frequency produced in said circuitby the normal speed of said motor, and electrical connections betweenthe cathode of said tube and the secondary of said transformer.

12. In combination, an electric machine having a stator and a rotor. atuned circuit, and means :omprising a thermionic device responsive tofluctuations in a characteristic of said machine through theintermediary of said tuned circuit for regulating a characteristic ofsaid machine.

13. In combination, a circuit to be regulated, a vacuum tube regulatorfor controlling a condition of said circuit and having an anode and acathode, a tuned circuit responsive to changes in a condition of saidfirst circuit, and means for supplying said cathode with heating currentthrough the intermediary of said tuned circuit.

14. In combination, an electric circuit, a translating device in saidcircuit, and means for holding substantially constant a characteristicof said device, said means compris ing an electric discharge devicehaving an anode and a cathode for controlling said electric circuit, atuned circuit responsive to variationsin a characteristic of saidcircuit. and connections responsive to said tuned circuit for varyingthe discharge characteristics of said discharge device.

15. A motor regulating arrangement comprising, a motor to be regulated,means for producing an alternating current having a frequency determinedby the speed of the motor, a circuit over which said frequency may betransmitted, said circuit producing a large change in attenuation for asmall change in frequency, means to translate the alternating currentinto an operating current proportional to the attenuation, said meanscomprising an electron discharge device, and means controlled by saidoperating current for varying the speed of said motor.

16. In combination, an electric machine having a stator and a rotor. afrequency selective circuit responsive to changes in characteristic ofsaid machine, and a vacuum tube regulator responsive to said circuit forregulating a characteristic of said machine.

17. In combination, an electric machine having a stator and a rotor, acircuit producing a large change in attenuation for a small change infrequency, and a vacuum tube regulator responsive to said circuit forregulating a characteristic of said machine.

18. In combination an electric circuit, a translating device in saidcircuit and means for holding substantially constant a charac teristicof said device, said means comprismg an electric discharge device havingan anode and a cathode for controlling said electric circuit, afrequency selective circuit responsive to variations in a characteristicof said circuit and connections responsive to said frequency selectivecircuit for varying the discharge characteristic of said dischargedevice.

19. In combination an electric circuit. a translating device in saidcircuit and means for holding substantially constant a characteristic ofsaid device said means comprising an electric discharge device having ananode and a cathode for controlling said electric circuit, a circuitproducing a large change in attenuation for a small change in frequencyresponsive to variations in a characteristic of saidcircuit andconnections responsive to said last mentioned circuit for varying thedischarge characteristic of said discharge device.

In witness whereof, I hereunto subscribe my name this 9th day of June A.D. 1919.

HUGH M. STOLLER.

